Griphin I guess didn't read you correctly before, sounds like you are already well into the game.
Using the solution solve is one of the times you do shoot straight out the front, zero gyro angle.
When you first load up the game all data in the TDC is set to 0 and you will shoot straight.
If you have used the TDC for another shot than you will need to reset to zero gyro angle. To do this:
set speed to 0 and send to PK.
set AoB to 0° and send to PK
set range to 1200 or so and put the periscope to 0° and send to PK.
To set range just pull the range triangle down far as it will go.
The solution solver is a neat little tool that is kind of fun to use.
Gutted put a lot of work into it and did a very nice job.
Once you get the hang of this tool it's very easy to use and very accurate as well.
Good luck and good hunting.
Magic